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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 429 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 1339 ÷ 28? (a) 450 (b) 4500 (c) 45
  2. 2.Best estimate of 4161 ÷ 76? (a) 52 (b) 520 (c) 5200
  3. 3.√77 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  4. 4.Best estimate of 2225 ÷ 42? (a) 56 (b) 5600 (c) 560
  5. 5.Best estimate of 3281 ÷ 42? (a) 8200 (b) 820 (c) 82
  6. 6.Best estimate of 3956 ÷ 76? (a) 490 (b) 4900 (c) 49
  7. 7.Best estimate of 1248 ÷ 24? (a) 62 (b) 620 (c) 6200
  8. 8.Best estimate of 3682 ÷ 86? (a) 410 (b) 41 (c) 4100
  9. 9.Best estimate of 1235 ÷ 66? (a) 180 (b) 1800 (c) 18
  10. 10.√80 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  11. 11.Best estimate of 1750 ÷ 24? (a) 880 (b) 88 (c) 8800
  12. 12.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 5.0 (d) 4.9
  13. 13.√62 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 7.8 (d) 8.0
  14. 14.Best estimate of 6728 ÷ 73? (a) 960 (b) 9600 (c) 96
  15. 15.Best estimate of 1597 ÷ 32? (a) 530 (b) 53 (c) 5300
  16. 16.Best estimate of 1647 ÷ 78? (a) 21 (b) 210 (c) 2100
  17. 17.Best estimate of 2382 ÷ 44? (a) 60 (b) 6000 (c) 600
  18. 18.Best estimate of 2285 ÷ 29? (a) 7600 (b) 76 (c) 760
  19. 19.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  20. 20.Best estimate of 2195 ÷ 46? (a) 440 (b) 44 (c) 4400
  21. 21.√35 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 6.1
  22. 22.Best estimate of 1703 ÷ 26? (a) 57 (b) 5700 (c) 570
  23. 23.Best estimate of 2917 ÷ 32? (a) 9700 (b) 97 (c) 970
  24. 24.√50 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.1
  25. 25.Best estimate of 2366 ÷ 58? (a) 390 (b) 39 (c) 3900
  26. 26.Best estimate of 4615 ÷ 71? (a) 6600 (b) 66 (c) 660
  27. 27.Best estimate of 947 ÷ 48? (a) 19 (b) 190 (c) 1900
  28. 28.Best estimate of 2204 ÷ 89? (a) 24 (b) 240 (c) 2400
  29. 29.Best estimate of 6155 ÷ 84? (a) 77 (b) 770 (c) 7700
  30. 30.Best estimate of 1452 ÷ 39? (a) 36 (b) 3600 (c) 360
  31. 31.Best estimate of 3509 ÷ 39? (a) 88 (b) 8800 (c) 880
  32. 32.Best estimate of 5319 ÷ 56? (a) 89 (b) 890 (c) 8900
  33. 33.√83 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  34. 34.Best estimate of 832 ÷ 39? (a) 21 (b) 210 (c) 2100
  35. 35.√72 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.6
  36. 36.Best estimate of 3028 ÷ 32? (a) 101 (b) 1010 (c) 10100
  37. 37.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  38. 38.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.2 (d) 9.4
  39. 39.Best estimate of 2419 ÷ 58? (a) 400 (b) 4000 (c) 40
  40. 40.√88 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.7 (d) 9.6

Answer key

  1. 45
  2. 52
  3. 8.8
  4. 56
  5. 82
  6. 49
  7. 62
  8. 41
  9. 18
  10. 8.9
  11. 88
  12. 4.7
  13. 7.9
  14. 96
  15. 53
  16. 21
  17. 60
  18. 76
  19. 9.7
  20. 44
  21. 5.9
  22. 57
  23. 97
  24. 7.1
  25. 39
  26. 66
  27. 19
  28. 24
  29. 77
  30. 36
  31. 88
  32. 89
  33. 9.1
  34. 21
  35. 8.5
  36. 101
  37. 9.1
  38. 9.3
  39. 40
  40. 9.4

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